A biomechanical comparison of initial sprint acceleration performance and technique in an elite athlete with cerebral palsy and able-bodied sprinters

Abstract

Cerebral palsy is known to generally limit range of motion and force producing capability during movement. It also limits sprint performance, but the exact mechanisms underpinning this are not well known. One elite male T36 multiple-Paralympic sprint medallist (T36) and 16 well-trained able-bodied (AB) sprinters each performed 5-6 maximal sprints from starting blocks. Whole-body kinematics (250 Hz) in the block phase and first two steps, and synchronised external forces (1,000 Hz) in the first stance phase after block exit were combined to quantify lower limb joint kinetics. Sprint performance (normalised average horizontal external power in the first stance after block exit) was lower in T36 compared to AB. T36 had lower extensor range of motion and peak extensor angular velocity at all lower limb joints in the first stance after block exit. Positive work produced at the knee and hip joints in the first stance was lower in T36 than AB, and the ratio of positive:negative ankle work produced was lower in T36 than AB. These novel results directly demonstrate the manner in which cerebral palsy limits performance in a competition-specific sprint acceleration movement, thereby improving understanding of the factors that may limit performance in elite sprinters with cerebral palsy.

The Biomechanics of the Track and Field Sprint Start: A Narrative Review

“…Proximal-to-distal sequencing is evident in peak stance leg hip, knee, ankle and metatarsal-phalangeal (MTP) angular velocities during the first stance phase [40, 70–72]. The stance leg MTP joint initially dorsiflexes during the first 10–15% of stance but is then relatively stationary until around 60–65% of stance, after which there is further dorsiflexion followed by a rapid plantar flexion (up to 500°/s), which peaks around toe-off [71, 72].…”

“…The stance leg knee continues to extend throughout the majority of stance towards peak extension angles of around 160–170° [30, 70–73], but not to full extension, likely due to both geometrical and anatomical constraints [75]. The transition to knee flexion typically starts within the final 10% of stance [40, 70–72], but this is not consistently the case, with some sprinters still extending their knee at toe-off [30, 71].…”

“…Having flexed from soon after rear block exit, the stance leg hip starts to extend slightly before touchdown [30] and continues to extend throughout stance [30, 40, 70–73]. For some sprinters, the hip starts to flex just prior to toe-off [40, 71, 72], although this is not always the case [30, 70, 71, 73]. There is also around 15–20° of hip abduction during stance as well as some internal rotation [30].…”

Classifying motor coordination impairment in Para swimmers with brain injury

“…4 The clinical features presented by athletes with brain injury include decreased central motor output, hypertonia, incoordination and coactivation of agonist and antagonist muscle groups, although the distribution and severity of these features varies considerably depending on the aetiology of brain injury. 4 Research has provided some understanding of how these clinical features impact on sport and exercise performance, [5][6][7] with performance deficits being attributed to losses in strength, 8 9 joint range of motion 10 and motor coordination. 11 Motor coordination, which is defined as the ability to produce skilled movement fluidly, rapidly and accurately is affected in Para athletes with brain injury.…”

Validity and Reliability of a Test Battery to Assess Change of Directions with Ball Dribbling in Para-footballers with Cerebral Palsy

“…Para-athletes who have ataxia (involuntary movements and impaired coordination), athetosis (involuntary contractions of the muscles) or dystonia (repetitive torsions and movements or abnormal postures) are individuals that have general problems with balance and performing departures, stops and turns during a race [35]. Accordingly, a recent study conducting a biomechanical comparison of the initial sprint acceleration performance and technique in an elite athlete with CP of this profile and able-bodied sprinters demonstrated the impact of this type of CP on performance in a competition-specific acceleration movement [36]. Therefore, when the ball is included during testing, driving it makes it more difficult to accomplish the task, constraining their motor control, and they take longer than the other sport classes.…”